It's no semantic twist. I reject objectivism. Christian morals are not objective in their own right, independant of Christ, such they they could be derived without reference to God's revelation in Christ. To use a physics analogy, just because everything is relative to the speed of light in the Theory of Revativity doesn't mean the calculations offer no definitive answers. I'm employing relative relativism, as Einstein would, rather than absolute relativism.
To illustrate this concept you may find the graph to you left of interest. It shows that while obsevers travelling at different speeds (one stationary, one travelling approximately 40% of the speed of light) may disagree over how long the driver's journeys took (one saying T, the other saying T'), the Theory of Revativity yields definite calculations for each of the perspectives. This is quite different to Newtonian physics which says T always equals T', no matter what speed the driver was doing.
In a similar vein, I think what God requires of us depends on where each of us are in our journey in relation to God, as revealed in Christ, and to one another. I recall a story of some early missionaries to Africa, who were trying to come to grips with polygamy amongst newly converted Christians. They were shocked to learn that the church had developed a reputaion for encouraging prostitution! How? Well, on hearing that Jesus saw the ideal marriage as comprising one husband and one wife, many were ditching the other wives. And how else were the ex-wives to support themselves? You guessed it! Rethinking the problem in relation to Christ and the culture, the missionaries concluded that polygamy was preferable to prostitution so Christian converts should be advised to NOT divorce any wives. It was enough that they should (1) be satisfied with the wives they already had and marry no more (2) teach the next generation to only take on one wife and (3) only appoint Christians in monogamous relationships as elders. Their answer was definite but their answer was relative to their circumstances. Their answer was Christ honouring but their answer – to accept polygamy amongst church members – was not black and white for all occasions.